Vernier for radiodials



E. B. LEWIS VERNIER FOR RADIODIALS Filed May 12. 1924 awuwnto'c Earle B.Lewis. w fiwaum Patented Oct. 12, 1926.

UNITED STATES EARLE B. LEWIS, or WATERBURY, coNNEcrIcun VERNIER FORRADIODIALS.

Application filed May 12,

This invention relates to radio apparatus, and more particularly to avernier attachment for tuning dials adapted to produce a fine adjustmentof condensers, variometers, and other tuning instruments.

One object of this invention is to provide a vernier attachment of theabove nature, which is adapted to be located between the tuning dial andthe panel of a radio set.

A further object is to provide a vernier attachment in which all of theworking parts except the operating knob, are entirely concealed by thedial.

A further object is to provide a device inexpensive to manufacture, easyto manipulate, compact in size, and very efficient and durable in use.

lVith these and other objects in view, there has been illustrated on theaccompanying drawings one form in which the invention may beconveniently embodied in practice.

Fig. 1 represents a front elevation of a radio panel and tuning dial,upon which the vernier attachment has been installed. 7

Fig. 2 is a side sectional view of the same. Fig. 3 is a view of thevernier lever and operating knob, shown apart from the remainder of thedevice.

Fig. 4 is a separate view of the friction late. p Fig. 5 is a separateview of the vernier lever and friction plate shown in their relativepositions.

Referring now to the drawings in which like reference numerals denotecorresponding parts throughout the several views, the numeral 10indicates the panel of a radio set, said panel being apertured at 11 toreceive av shaft 12 of a tuning instrument, not shown, such as acondenser, variometer, or the like.

In order to permit the tuning instrument to be roughly adjusted, atuning dial 13 is mounted on the outer end of the shaft 12 in front of,and spaced from, the panel 10. The dial 13'has a central recess 14extending into its rear face, said recess being fitted over the shaft12. The dial 13 is detachably secured in position upon the shaft 12 by ascrew 15, which is threaded in a countersunk passage 16 in the lowerpart of a knob 17. The knob 17 is preferably knurled in order to permitthe dial to be readily manipulated for roughly tuning the instrument.The dial 1924- Serial No. 712,841.

13 is provided with a thin beveled rim having a suitably graduated scale18 extending for a half-circumference. A reference mark 19 is located onthe panel above the dial.

In order to permit a finer or more accurate adjustment of the dial,after the rough adjustment'just referred to has been performed,provision is made of a vernier attachment comprising a vernier lever 20and a friction plate 21, referably constructed from flat sheet metal Thevernier lever 20 is provided'with straight end portions 22 and 23 and anintermediate enlarged sec- S tion 24:. The enlarged section 24 issubstanof the above nature which will be simple,

tially oval-shaped, and'has an arcuate cutout section25, the sides ofwhich are equal- 1 1y spaced from the shaft 12,-previously mentioned.The vernier lever 20 is provided at its upper end with a rearwardlyprojecting pin 26, said pin beingpivotally seated in a recess 27 formedin the panel 10. The lower end of the vernier lever 20 is provided witha small operating knob 28 extending away from the direction of thepanel, and

suitable manner.

A' pointer 29' is provided on the extremity of the vernier lever belowthe knob 28, and said pointer is adapted to rotate in front of acircular scale 30 located on the panel be low the dial 13,.as clearlyshown in Fig.1. In order toprevent the vernier lever from scratching thepanel, the lower end of said lever is offset forwardly, as most clearlyshown in Fig. 2, and provided with apad 29 of'felt or other softmaterial.

The central position of the vernier lever is clearly shown in full linesin Figs. 1 and 5, while the extreme positions of said lever are shown bythe dotted lines '31 and 32 of Fig.

said knob being secured in positionin any 5. The upper extremity of thevernier lever is providedwith a small forwardly project ing lug 33, saidlug being adapted to slidably fit within a slot 34 formed on the upperend of the friction plate 21, previously mentioned. The lower end of thefriction plate is provided with a slot 35 similar in all respects to theslot 34.

The side arms of the slots 34 and 35 are provided with circular recesses36 and 37 respectively, the recesses 37 being of somewhat largerdiameterthan the recesses 36.

ameter, the friction plate 21, of course, being reversed from theposition shown in Fig. 5, when used on said smaller shaft. In eithercase, the diameter of the circular recesses is made slightly smallerthan the diameter of the shaft upon which the friction plate is to bemounted, so that the side members of the slots will resiliently grip theshaft. I

The central position of the friction plate 21 is shown in full lines inFig. 5, the estren'ie positions of said plate being shown by the dottedlines 38 and 39. It will thus be seen that when the lever is operated,the angular rotation of the friction plate 21, and consequently that ofthe tuning dial 13 which is frictionally connected therewith, will bevery small compared with the angular rotation of the Vernier lever 20.In other words, a relatively large movement of the Vernier lever 20 willresult in a relative] y small movement of the tuning dial 13.

It will be noted that since the vernier lever 29 and the friction plate21 are pivoted upon different fulcrums, the smaller the distance betweenthe pin 26 and the lug 33, the greater will be tl mechanical advantageand sensitiveness of the vernier attachment. The vernier attachmentshould, however, be preferably so designed to give a mechanica advantageof ten, so that movement of the vcrnier lever 20 from one extremeposition to the other (about points of the scale 30) will cause thetuning dial 13 to rotate only about five points on the scale 18.

In operation, when the Vernier lever 20 is rotated to the right, the lug33 will move to the left, and by reason of its sliding engagement in theslot 3% of the friction plate 31, will cause said plate to move in thesame angular direction. The shaft 12, which is resiliently clamped bythe friction plate 31 will also rotate in the same direction, carryingthe dial 13 with it. The friction plate 21 is preferably so designedthat while the friction on the shaft is sullicient to cause the tuningdial to rotate in response to a movement of the vernier lever, saidfriction will be insuiiicientto cause the V6I'I1l6IlSVGI' to move whenthe dial is being manipulated specification one form in which theinvention may be embodied, it is to be understood that this form isshown for the purpose of illustration only, and that the invention 15not to be limited to the specific disclosure but may be modified andembodied in various other forms without departing from its spirit. inshort, the invention includes all the modifications and embodimentscoming within the scope of the following claims.

Having thus fully described the invention, what is claimed as new, andfor which it is desired to secure Letters Patent, is:

1. In a radio tuning device, a shaft adapted to extend through a panel,a dial on said shaft, a slotted plate havin its side arms clampingfrictionally on said shaft, a lever having a lug slidably fitted in saidplate, said lever having a fulcrum supported by said panel, the rotationof said lever causing said plate and'dial to turn in the same direction,but through a much smaller angular amount, both ends of said platehaving slots, said slots having enlarged recesses of differentdiameters, to permit said plate to be interchangeably and resilientlyclamped on sha ts of different diameters.

2. In a radio tuning device, a shaft, a plate on said shaft, said platehaving slotted ends communicating with enlarged recesses of differentsizes, an operating lever, said lever carrying a pin for engaging saidplate, the slotted ends of said plate being adapted to frictionallyengage said. shaft whereby the rotation of said lever will cause saidshaft to rotate, the opposite ends of said plate being adapted to beinterchangeably clamped on shafts of different diameters.

3. In a radio tuning device, a shaft, a plate having a plurality offrictionally gripping slotted sections for clamping upon shafts ofdifferent diameters, an operating lever, means on said lever forengaging said plate in a slotted section other than that whichfrictionally grips said shaft at a point eccentric to the fulcrum ofsaid lever whereby the rotation of said lever will cause said shaft torotate through a different angular amount.

In testimony whereof, I have affixed my signature to this specification.

EARLE B. LE'WI

